1. Technical Field
The present invention relates to workstation skillet lift systems and methods of mechanically lifting a skillet borne object, and more particularly, to a mechanical workstation skillet lift operable to autonomously convert the translation of the skillet into the controlled lifting of the object, and a conveyor system comprising the same.
2. Discussion of Prior Art
Skillet conveyor systems have long been developed to increase the efficiency of manufacture and construction in industry. Generally, these systems comprise pluralities of stationary workstations and mobile skillets (or carriers) that sequentially enter each workstation. For example, a conveyor system may require 80 to 100 active workstations in 4 to 6 lanes, and 100 to 120 skillets. The work in progress (or object) is transported together with the skillet to each station where an operator awaits to perform a task. The need to lift the object, based on the task being performed and/or the height of the operator, often necessitates the inclusion of skillet borne lifting mechanisms. A main drive system, such as a conventional side-pusher drive, is provided to propel the skillets along the conveyor path. A communication system typically including an encoded rail and a PLC configured control module on each skillet is provided, so that each workstation is able to discern the entry of a skillet into the workstation. As such, sensory technology, such as a photo-eye and reflector, is also communicatively coupled to the control module. Finally, power is distributed to each skillet through a buss rail; and collector shoes on each skillet are fed into and out of the buss rail for each production run.
With respect to the lifting mechanism, a separate drive is typically dedicated to the lift. For example, in one conventional scissor lift configuration, a skillet borne electric motor causes a longitudinal shaft to rotate. The shaft is connected to a lateral axle and configured to wind at least one belt around the axle. The belt is configured and inter-aligned with the scissor apparatus, so as to cause a linearly translatable pair of scissor legs to migrate when the belt is wound. The migration of the legs causes the apparatus and a table attached thereto to rise or descend. The motor is precisely actuated and de-activated to effect the proper lift, and as such is communicatively coupled to the control module and power buss.
It is appreciated by those of ordinary skill in the art that the inclusion of communication and sensory technology, however, adds implementation and operational costs to the overall conveyor system; and when multiplied by the number of skillets and workstations, these costs are magnified. More concernedly, when carriers are in transit or in buffer positions, they invariably carry these investments without utility. It is also appreciated that the necessary inclusion of communication and sensory requirements results in a more complex system to install and operate, and a less flexible system to modify.
Purely mechanical skillet lifts that do not rely upon an electric motor, computer actuation, or communication with the station have recently been developed to address these concerns; however, they too present operational limitations. For example, a recent type of mechanical skillet lift includes ramp and wheel engagement to effect a minimal lift. In this configuration, however, the result of moving up a ramp puts back pressure on the line of skillets through a production area, causing them to try and separate. Similarly, the translation force when on the down ramp causes the skillets to separate. As a result, the skillets are typically locked together while moving through an assembly area, which reduces process flexibility and decreases operational efficiency, and the carriers have to be unlocked for transport between lanes. Finally, the minimal lifting ranges afforded by conventional mechanical lifts are insufficient for many applications and processes.